Roof mounted skylights in the prior art suffer from the drawback that if they are not painstakingly installed, run-off water from the skylight will leak between the skylight and the roof, thereby causing water damage to the structure under the roof. Conventionally, skylights comprise a transparent or tranluscent window mounted in a frame. The skylight is mounted so as to close an aperture in the roof between the roof support trusses. The frame of the skylight follows the perimeter of the aperture in the roof. Flashing is placed around the frame to divert run-off water from the skylight onto the outer surface of the roof.
Some skylights at present available in the marketplace include built-in flashing as an integral part of the skylight frame. These skylights are referred to as "self-flashing" skylights. Self-flashing skylights also divert run-off water onto the outer suface of the roof.
Self-flashing skylights work very well on roofs having a thin cross-sectional thickness and a relatively flat outer surface. However, conventional self-flashing skylights are not well adapted for use on roofs having large cross-sectional thickness due to non-uniform outer surfaces such as concrete, slate or clay tile. Currently, the procedure to mount a skylight in this type of roofing requires the penetration of the roof and the construction of a wood "curb" in the resulting aperture. The skylight is then mounted on the curb.
Constructing a curb adds to the expense. But without the curb, difficulty is encountered in draining the water away properly to the roof surface, in the case of thick roofs.
The present applicant avoids the foregoing problems by providing a self-flashing skylight structure that drains, at least in the vicinity of the skylight, internally rather than externally, relative to the outer surface of the roof.
U.S. Pat. No. 4,194,325, Chalpin Jr., issued 25 Mar., 1980, teaches collecting run-off water in secondary gutters 12, and passing the run-off water through drainage holes in the secondary gutters, into the primary gutters 10 , which in turn direct the water to the perimeter gutter 16. The water is then conducted to appropriate conduits, or the like, for disposal thereof. Chalpin Jr. does not disclose roof-embedded gutters for conveying water beneath the roof structure.
U.S. Pat. No. 4,776,141, Powell, issued 11 Oct., 1988, provides ribs 17 on flange 16, said ribs forming channels to carry away from the opening for the skylight unit any water which may pass through the roofing material. The Powell patent does not, however, disclose the idea of carrying the water away from the skylight underneath the roof.
Japanese patent specification no. 109,222, Ishibashi, published 27 Aug., 1979, discloses a skylight having dew groove 3 which communicates with drain pipe 4. Drain pipe 4 drains water from groove 3 onto the outside of roof 6. Again, the idea of carrying water away from the skylight underneath the roof is not taught.
Canadian patent no. 1,201,264, Robertson, issued 4 Mar., 1986, teaches a system of channels for directing water away from a skylight. However, there is no disclosure of roof-embedded gutters for conveying water beneath the roof.